US 2010/0066426 A1 discloses that alternating current (AC) capacitive coupling strategies are commonly used in the data acquisition (DAQ) signal paths of positron emission tomography (PET) systems using, for example, a scintillation crystal in optical communication with a plurality of photomultiplier tubes (PMTs) for sensing incident gamma rays. In such systems, the energy absorbed from a gamma ray interacting with the scintillation crystal is measured by integrating the photosensor current. This current represents the amount of light collected by the sensing PMTs. Because of the AC coupling, only the AC portion of the photosensor current is passed to the integrator while the direct current (DC) portion is effectively blocked by a coupling capacitor. This has the disadvantage of causing a count rate dependent baseline shift or wander in the integrated photosensor current signals, which, in turn, can lead to incorrect energy measurements. In order to mitigate these adverse effects, a baseline restoration circuit comprising a passive network is integrated into the DAQ signal path. However, this circuit may not always be able to sufficiently correct the baseline shift induced by the AC coupling.